Radiation Effects Modeling and Experimental Data on I2L Devices

This paper reports on an Integrated Injection Logic (I2L) radiation effects model which includes radiation effects phenomena. Twenty-five individual current components were identified for an 12L logic gate by assuming wholly vertical or wholly horizontal current flow. Equations were developed for each component in terms of basic parameters such as doping profiles, distances, and diffusion lengths, and set up on a computer for specific logic cell configurations. For neutron damage, the model shows excellent agreement with experimental data. Reactor test results on GE I2L samples showed a neutron hardness level in the range of 6 x 1012 to 3 x 1013 n/cm2 (1 MeV Eq), and Cobalt-60 tests showed a total dose hardness of 6 x 104 to greater than 1 x 106 Rads(Si) (all device types at an injection current of 50 microamps per gate). It was found that significant hardness improvements could be achieved by: a) diffusion profile variation, b) utilizing a tight N+ collar around the cell, and c) locating the collector close to the injector. Flash X-ray tests showed a transient logic upset threshold of 1 x 109 Rads(Si)/sec for a 28 ns pulse, and a survival level greater than 2 x 1012 Rads(Si)/sec.